Reference is made to provisional patent application Ser. No. 60/013,879 filed Mar. 22, 1996.
The field of the invention pertains to plastic injection molding, and in particular, to plastic injection molding machines.
A typical plastic injection molding machine utilizes a plasticizer screw to melt and move the plastic material, a mold, a gate for the mold and an injector to place the material in the mold. The above components of the machine are connected via a flow channel for the molten material. Hot runner flow channel manifolds are sometimes used to keep the material in a molten state during delivery.
Such a plastic injection molding machine is disclosed in U.S. Pat. No. 4,734,243. This machine includes a plurality of plunger injection devices, one for each mold.
Unfortunately, non-repeatability and the ensuing quality degradation therefrom are sometimes observed with multiple parallel flow channels leading to multiple molds. Part of the problem is the non-Newtonian behavior of polymers which vary in viscosity with flow rate. Variation in tip temperature and flow impedance in the mold cavity are other contributors to the problem.
Therefore, a more effective injection molding machine and method for molding is an advantageous goal. Such a more effective machine and method are disclosed below.